STAND DESCRIPTION
- Plot Name: Reference Stand 31 (HJA)
- Plot Size: 1 ha
- Established: 1978
- Remeasurements: 1983, 1988, 1995
- Site Description
- Latitude: 44.26
- Longitude: 122.18
- Elevation: 900 m
- Aspect: S-SE
- Slope: 20-25%
- Landform: Bench adjacent to ridge
- Soil Parent Material: Greenish tuffs and breccias
- Soil: Budworm Series
- Plant Association: Tsuga heterophylla-Abies amabilis/
Rhododendron macrophyllum/Berberis nervosa
- Age Class: Old-growth
Soils:
Soils at two profile pits were described and sampled
(see profile nos. 298 and 317 in the HJA Soils Data Base).
The surface soil consists of 13 to 16 inches of very dark
brown to very dark grayish brown silt loam with small amounts
of shot. A thick B2 horizon is made up of dark yellowish
brown silty clay loam which is largely stone-free. The C
horizon is not encountered until at least 50 inches in depth.
These deep soils are moderately well drained to well
drained.
General Stand Description:
RS 31 is an old-growth representative of the upper-
slope climatic climax habitat type. The description of plot
vegetation is derived from the tree stem map and four
understory circular plots for the shrubs and herbs.
The tree layer is an uneven layered canopy composed of
a broken layer of Pseudotsuga menziesii old-growth trees
(over 450 years of age) and scattered emergent Tsuga
heterophylla. A secondary tree layer is much denser and
composed of multiple age-classes of Tsuga heterophylla and
scattered Abies amabilis and Thuja plicata. Tsuga
heterophylla is the dominant reproducing tree with Abies
amabilis secondary.
The shrub layer is dominated by Acer circinatum, with
scattered Rhododendron macrophyllum. Vine maple cover is
greater than typical for this type, but its growth is
fostered by an open tree canopy and a south aspect. Low
shrub cover is dominated by Berberis nervosa.
As is common for this habitat type, the herb layer is
poorly developed. The only species of note is Linnaea
borealis, which has a patchy distribution.
- Stand Structure and Composition
- Live Tree Data at Last Measurement (1995)
- Basal Area: 95.4 m2/ha
- PSME-58.5 m2/ha
- TSHE-31.8 m2/ha
- THPL-4.4 m2/ha
- Stem Numbers: 535/ha
- TSHE-432/ha
- PSME-51/ha
- THPL-13/ha
- ABAM-10/ha
- Diameter Distribution:
- median-16.7 cm.
- quadratic mean-47.7 cm.
- max.-195.0 cm.
- Age: not available
- Height: not available
- Volume: 1692.3 m3/ha
- PSME-1136.2 m3/ha
- TSHE-485.1 m3/ha
- THPL-64.4 m3/ha
- Biomass: 908.2 Mg/ha
- PSME-655.9 Mg/ha
- TSHE-227.2 Mg/ha
- THPL-21.4 Mg/ha
- Coarse Woody Debris (measured in 1995):
Log volume and mass on reference stand 31 are 649 m3/ha and
152 Mg/ha, respectively. Snag volume and mass are 103
m3/ha and 27 Mg/ha, respectively.
- Ecosystem and Population Dynamics (measurements for most recent
interval, 1988-1995)
- Net Bole Production: 6.1 Mg/ha/yr
- Annual Mortality: 9.1 Mg/ha/yr
- Percent of Trees Dying: total-0.5%/yr